No no. Dont use those plastic wall plugs. They might get loose and come out in the course of time. Use wooden pieces for this purpose. My electrician did this job for me and he stated that these plastic plugs are not advisable for heavy usage...
I can only smile at the old fashioned ideas that the electrician tells you and that you believe in.
Wood tends to rot and lose it's grip. In time, you can just pull it out with your hand. Even if you use something like teak, as you insert a screw, you are splitting the wooden plug into multiple pieces that can easily slip. I have used plastic wall plugs all over my house and they have been there for over 14 years now without issues.
A wooden plug is easy for electricians and others as it does not need accuracy. If the screw does not fit properly, you can simply reposition the the screw, or hammer it in at an angle. With plastic wall plugs, you have to mark the walls accurately. You cannot turn the screw in sideways, and you do not have more a few mm as leeway. A wooden screw is also the only option for electricians who do not use electric drills to create accurate holes in the wall.
A plastic wall plug will never rot. In addition, as you turn the screw in, the plug actually expands inside and grips the sides of the hole in the wall. If you are very particular, you can actually paste a little amount of glue such as Fevicol on the plug before you insert it into the wall.
If you are uncomfortable with plastic, you can also use metal plugs that are available today and that come with the right size bolt.
Cheers